Note: Descriptions are shown in the official language in which they were submitted.
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RECEIVER DRYE~
Technical Fi~ld
The present invention relates to receiver
dryer devices, particularly for vehicular air-
conditioning systems, for separating moisture-laden,
partially vaporized refrigerant fluid into a moisture-
free refrigerant vapor having a pre-determined, specific
lubricating oil content.
Back~round of Invention
In most any refrigeration system, and
certainly any vehicular air-conditioning system, the use
of a receiver dryer at the outlet end of the condenser
is an alternative to the use of an accumulator at the
outlet end of the evaporator. The receiver dryer
receives refrigerant fluid, typically freon~l2, at a
high pressure (e.g. 200 psig) and high temperature (e.g.
150-F) and filters any particulates in the fluid and
removes any moisture or water which may be present in
the refrigerant fluid. At the outlet end of the
receiver dryer, the refrigerant fluid is passed through
an expansion device or valve and thereby transformed to
a vapor of low temperature (e.g. 50'F) and pressure
(e.g. 40 psig), prior to it being passed through the
evaporator. Typical examples of such a system are shown
in U.S. Patents 4,649,719; 5,038,582 and 4,908,132.
Closely related apparatus are accumulators
located downstream of the evaporator and used as an
alternative to a receiver dryer, each serving the common
purposes of filtering particulates and removing water
from the refrigerant and each also acting as a storage
reservoir for the refrigerant fluid when the system is
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FTP 0102 PUS
disengaged. One example of a highly efficient, fairly
economically manufactured receiver dryer is shown in
U.S. Patent 4,675,971 assigned to the assignee of the
present invention, wherein a cylindrical, aluminum
housing is completely closed at its bottom end by a
spinning operation, is loaded with a desiccant material
and perforate disc-shaped member, and then capped with
a top containing inlet and outlet tubular members.
The present invention maintains the functional
efficiency of such known devices, but includes fewer
components and a simplified and more reliable method of
manufacture.
8ummarY Of The Invention
The present invention contemplates a receiver
dryer member for a refrigeration system, particularly a
vehicular air-conditioning system, of the simplest
construction and containing a minimum number of
components, yet being the full, functional equivalent of
known receiver dryer devices.
The invention further contemplates a receiver
dryer member as described above, having enhanced
reliability resulting from its simplistic structure and
method of manufacture.
The invention further contemplates a receiver
dryer constructed in such manner that the final
manufacturing step of spin closing the bottom open end
of the receiver dryer housing generates sufficient heat
to thermally form the thermoplastic perforate
particulate filtering element to the housing and thereby
also provide an ideal seal between the filter element
and dryer housing where desired.
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. The invention further contemplates a receiver
dryer structure and method of manufacture whereby the
use of a desiccant material containing cartridge, which
may optionally include in combination a particulate
filter element, is facilitated.
Brief DescriPtion of the Drawinqs
FIGURE 1 is a schematic representation of a
- typical vehicular air-conditioning system incorporating
use of a receiver dryer as may be designed pursuant to
the present invention;
FIGURE 2 is an elevation view of the present
invention shown partially in cross-section taken along
section lines 2-2 of Figure 3;
FIGURE 3 is a plan view of the present
invention;
FIGURE 4 is an enlarged cross-sectional view
of the encircled area designated 4 in Figure 2;
FIGURE 5 is an exploded view of the receiver
dryer as shown in Figures 2 and 3;
FIGURE 6 is a perspective view shown partially
in section of a desiccant material containing and
particulate filter combination cartridge unit of known
construction suitable for use with the present
invention;
FIGURE 7 is a partial cross-sectional view
taken along section lines 7-7 of Figure 6; and
FIGURE 8 is a schematic block diagram of the
method of manufacture of the receiver dryer in
accordance with the present invention.
~est Mode for Carryin~ Out Invention
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Referring to Figure 1, there is a generally
conventional vehicular air-conditioning system
comprising a compressor 12, condenser 14, expansion
device 16, evaporator 18 and a receiver dryer generally
designated 20. A refrigerant fluid, such as freon-12 or
the like, is circulated through the system beginning as
a high temperature/high pressure vapor on the outboard
side of the compressor 12, then passing through the
condenser 14, during which time additional heat is taken
out of the vapor forming a high temperature/high
pressure liquid, then passing through a receiver dryer
constructed in accordance with the present invention,
then passing through an expansion device or orifice tube
16 such as that which is commonly termed an "H" valve
causing thermal expansion of the refrigerant and thereby
producing a low temperature/low pressure vapor/liquid
stream passing through the evaporator 18 which takes in
heat from the heated vehicular passenger compartment and
transforming the refrigerant to a low temperature/low
pressure vapor.
As shown in Figures 1-4, the receiver dryer 20
of the present invention includes a cylindrical tubular
housing 22 which is spun closed at both ends as
indicated by the dimples 24 located on the longitudinal
axis 26 of the housing member and formed as a result of
the spinning operation. Preferably, an aluminum alloy
such as SAE 6000 Series, such as 6063 T6, or its
equivalent is used, which is readily adaptable to the
manufacturing techniques discussed in detail below and
provides a light-weight component which is of great
demand in the automotive industry. An inlet tube 28 and
an outlet tube 30 extend through the top end wall 32 to
different points within the chamber 34 defined by the
housing enclosure. Both the inlet and outlet tube are
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disposed parallel to the longitudinal axis 26 of the
housing and the axis of each is located on a common
center line 36. The outlet tube 30 extends to the
bottom or opposite end 38 of the housing and includes a
discharge end 40 located at a pre-determined distance
from the bottom of the housing. The inlet tube 28
includes a discharge end 42 which is located near the
uppermost regions of the chamber 34. Within the chamber
34 of the receiver dryer housing is located a desiccant
material containing member 50. Conventionally, such a
member would include a flexible perforate cloth bag 52
filled with granules 54 of silica gel or calcium
chloride. The desiccant material containing member is
supported within the chamber 34 by a perforate
thermoplastic filter element 60 made of sintered
polypropylene pellets 62 or equivalent material such as
high-density polyethylene, ultra high molecular weight
polyethylene, polypropylene, polyvinylidene fluoride,
ethylene-vinyl acetate, polytetrafluoroethylene,
stryene-acrylonitrile, or nylon.
As seen in Figure 4, the interstices 63
between the sintered pellets 62 form a tortious flow
path for refrigerant fluid and provide an effective
filter for catching any particulates. Generally, the
filter 60 may be produced with an effective sieve size
ranging from about 10 microns to about 100 microns. For
most automotive air conditioning systems, a design
specification of about lS microns is preferred, i.e.
particulates 15 microns and larger are precluded from
passing through the filter.
As seen best in Figures 2 and 4, the inlet and
outlet tubes 28, 30 extend through the respective inlet
and outlet ports 70, 72 and upon being positioned for
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their respective lengths are brazed to the housing as
indicated at 74.
The filter element 60 may temporarily be
maintained in place on the outlet tube by means of a
one-way slip fit-type lock washer 76 as shown in Figures
2 and 4. However, as explained in detail below, the
permanent position of the filter element 60 relative to
the housing is maintained by means of thermally forming
the filter element to the internal wall of the housing.
The necessary heat to partially melt or soften the
filter at the interface in contract with the internal
housing wall is generated during the final assembly step
of spin closing the bottom end 38 of the housing. This
generates conductive heat in the housing wall in the
area of the filter element in the order of 300~ to
about 400F, whereas the temperature at the bottom end
38 may be about 1100~.
It will be noted from the enlarged view of
Figure 4 that the housing internal wall includes
numerous surface irregularities 64. These are normal
irregularities produced during forming, as by extruding,
the cylindrical housing. As the housing is spun to
close off end 38, the outer rim portion of the filter,
softened by the conductive heat of the closing off
operation, is caused to centrifugally flow into these
surface irregularities 64, completely filling them and
thereby fixing the position of the filter 60 to the
housing by this thermal forming operation and providing
a complete and ideal seal at the thermally formed
interface of the filter and housing.
As shown in Figure 5, the dual component
combination of the desiccant material containing member
or bag 50 and the thermoplastic particulate filter
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element 60 can be replaced by a combination cartridge unit
such as shown in Figure 6.
The cartridge 80 includes the annular disc-like filter
60 previously described and including an annular bead or rim
portion 82. Rim portion 82 defines a shoulder 84 with the
upper end of the filter over which a retainer ring 86 may be
press-fitted to retain therebetween a portion of the
perforate filter bag 52 thereby retaining the desiccant
granules 54. Alternatively, the construction of the
cartridge 80 maybe conventional and represent no part of the
present invention except to the extent that it include an
outer plastic rim portion selected of a material such as
polypropylene or other similar material described above, so
that the seal and thermally formed bond at the annular rim
portion 84 of the cartridge unit will be established during
the spin closing of the end 38 of the housing.
As shown schematically in Figure 8 the process or
method of manufacture of the receiver dryer in accordance
with the present invention includes the following steps:
100. selecting an open-ended aluminum cylindrical tube
of 6063 T6 aluminum material or equivalent;
102. spin closing one end 38 of the housing, the spin
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closing technique being conventional in the art as taught in
U.S. Patent 4,675,971, for example:
104. drill inlet and outlet ports 70, 72 in the end
wall 32 of the housing to the same size of the outer
diameter of inlet and outlet tubes 28 and 30, respectively;
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106. insert inlet and outlet tubes through
their respective inlet and outlet ports, fixing them at
the relative length established for the discharge end of
each;
108. brazing each at 74 to the end wall 32 of
the housing;
110. axially inserting a desiccant material
containing member 50 to a point in proximity with the
discharge end of the inlet tube 28;
112. axially inserting an annular
polypropylene, or similar, perforate filter element 60
within the chamber until they point approximately mid-
way of the longitudinal axis of the chamber 34 defined
by the housing, with the filter element including a slot
or hole 61 allowing it to slide upon one length of the
outlet tube and optionally temporarily secured thereto
by means of a mechanical fastener, such as a push-on
type, one-way locking washer member 76;
114. finally, spin closing the remaining open
end of the housing and generating sufficient heat within
the housing as a result of the spinning operation, in
the order of about 300~ to about 400~ at the filter
element 60, to thermally and centrifugally form and
thereby bond and seal the annular outer rim 82 of the
filter element 60 to the internal wall surface of the
housing 22 using the spin closing technique as applied
to closing the other end of the housing (step b.)
Although particular embodiments of the present
invention have been illustrated in the accompanying
drawings and described in the foregoing detailed
description, it is to be understood that the present
invention is not to be limited to just the embodiments
disclosed. Numerous rearrangements, modifications and
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substitutions are possible, without departing from the
scope of the claims hereafter.
